Machine-switching telephone system



c. L. GOODRUM. MACHINE SWITCHING TELEPHONE SYSTEM.

APPLICATION FILED APR. 27 I9I7- v 1,393,521. Patented Oct. 11, 1921-.

2 SHEETS-SHEET I.

' lnwn for: Char/es L Gaadrum.

C. L. GOODRUM. MACHINE SWITCHING TELEPHONE SYSTEM.

APPLICATION FILED APR. 27,19]?- Patented Oct. 11, 1921.

2 $HEETSSHEET 2.

Mwnfar: (/1 dr/es L Goodrum.

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UNITED STATES PATENT OFFICE.

CHARLES I. GO ODRUM, OF'NEW YORK, N. Y., ASSIGNOR TO WESTERN ELECTRICCOM- IPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

MACHINE-SWITCHING TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented Oct. 11, 1921.

Application filed April 27, 1917. Serial No. 164,870.

To all whom it'may' concern:

Be it'known that 1, CHARLES L. GooDRUM, a citizen of the United States,residing at New York, in the county of New York and State of New York,have invented certain new and useful Improvements in Machine- SwitchingTelephone Systems, of which the following is a full, clear, concise andexact description.

This invention relates to machine switching telephone systems, and moreparticularly to improvements in group selecting switches for use in suchsystems.

The object of the invention is to provide an arrangement for"eliminating the trunk hunting interval in the operation of a group of aselecting switch.

A feature of the invention is the use of switching means somewhatsimilar in construction to the well known Keith line switch (U. S.Patent No. 1,151,543), in a directively actuated selector switcGenerally stated, the invention comprises a plurality of banks ofcontacts, each bank beingunder control of a plunger, means 'for keeping.the plunger-s always in operative relation with-sets of contacts whichare connected to idle trunks'and 'a means 'for selectively actuatinganyone of said plungers.

Through such means an idle trunk is instantly available for theextension of a connectionat the end o'f'the' group selecting operation,and the trunk hunting operation is entirely eliminated.

- In the drawings, Figure 1 is a diagrammatical perspective view of astructure embodying this invention showing in part the necessaryelements forming two switching mechanisms; F ig.-2is a-diagrammaticalrepresentation of a path through which a connection between twosubstations may beestablished, showing an indicated calling subscriberssubstation, an indicated-line switch, a group selector embodying thisinvention, an indicated connector switch, and an indicated calledsubs'cribers substation.

Each group selector switch consist-s essentially of a plurality ofplungers, such as P and P each place'd'in operative relation to aplurality of sets of contacts,such'as G and C or C and 0*. Certaincontacts in e'ach set are common to the line L the other cor l'tactsbeing individual ito the trunks, such as T 21?, (I and I- so that theactuation of the plunger fl iiwei; the .liiig teithr trunk T or Toperative relation with a pin 5 or 6 associated' respectively with theplungers P and P At the end of the rotating movement ofthe shaft 1, themagnet 7 is actuated, and,

through its armature 8, presses on, a disk 9 and moves the shaft 1downwardly. A pin on the shaft, such as 3, is thereby brought intoengagement with a pin, such as 5, as sociated with a plunger, such as Pwhich, engaging the contacts, such as C connects the line L with thetrunk T The trunk T now having been made busy, the magnet 10 will beactuated in amanner to be described hereinafter, and allows the rotationofthe "plunger bar 11 on its axis, so'as to bring another plunger, suchas P, still in engagement therewith, into operative relation withanother set of contacts connected with an idle trunk. Whenthe plungerbar 11 has been rotated through its full arc, means, hereinafter to be.described, cause the energization of magnet N, whereby the bar 11 isreturned to the position shown or normal.

It is thought that the invention may be more fully understood through adescription of the establishment of a connection employing a groupselecting switch of this nature.

Referring especially to Fig. 2, S represents the calling subscriberssubstation. hen the receiver is removed from its hook, the connectionwill be-extended to the group selector through a line switch indicatedat LS in the well known manner, whereupon a circuit will be establishedfrom battery, the left-hand winding of relay LR, the normal contact ofSON through the circuits of the line switch and the substation S to thenormal contact of SON the right-hand winding of relay LR to ground.Relay LR becomes energized in this circuit and attracts its armature,whereupon a circuit is established for the energizing of the first 510W"M y zirom. ground, armature and manipulates his sender, the resultingseries of breaks in the circuit through which relay LR is energizedcause the lnterrnlttent deenergization and energizatlon of relay LR anda consequent vibration of its armature.

Upon the first retraction-acircuit is established from ground, thearmature and normal contact of relay LR, the armature and alternatecontact of relay FS, the lower armature and contact of relay 7 to apoint where the circuit divides, extending in one direction through thewinding of the second slow relay SS to battery and ground, and in theother. direction through the winding of primary magnet PM to battery andground. Slow release relay SS becomes energized and holds its armatureattracted until after the last impulse has been re ceived and itscircuit is permanently opened. Relay PM, however, responds to eachseparate impulse, and, in the manner before described, rotates the shaft1, whereby a group of trunks is selected.

Shortlyafter the receipt ofthe last impulse, the second slow relay SSretracts its armature and establishes a circuit from ground, thearmature and contact of-relay SS, the primary off-normal contact PONthrough the upper winding of relay 7, the brush B, contact 12, uponwhich the brush B has been set by the rotation ofshaft 1, to the contactand right-hand armature of relay 10, the normal contact and left-handarmature of relay 13- to battery and ground.- Belay 7 becomes energizedin'this circuit and causes the plunger to operate the contacts G in themanner heretofore described. Atthe same time relay 7 attracts itsarmatures, opening at itslower armature and contact the circuit throughwhich relays SS and PM were energized, and completing throu h its innerarmature a holding circuit or itself, extending from groundfbattery, the

lower winding of relay 7, the inner armature and contact of relay 7, theleft-hand armature and contact of release relay R to ground. Themovement caused by the energization of relay 7 operates the secondaryoff-normal contacts SON SON and SON', whereby the calling line isextended through the contacts C to thetrunk T, and thence to theconnector switch OS. A further manipulation of the sender at thesubstation S directs the operation of a connectorswitch CS to theterminals of the called line S whereby the connection between these twosubstations is completed.

When the set of contacts (2 was operated a ground was extended throughthe springs 14 and 15' -to the conductor 16, and thence to the firstcontact 17 and brush 18, whereby it was further extended through thecontact its next position,

left-hand armature of relay 10, Winding of relay 1O tothe normal contactand lefthand armature of, relay 13; to "batteryj'and ground. Relay 10becomes energized in this circuitand escapesthe plunger bar 11 intowhereby the brush 18 is brought into operative relation with the nextcontact 19; i

' The brushes 18 and 20 attached to the bar 11 form a master switcharrangement whose function is to keep the plungers P and P before anidle trunk. Thuswhen contact 17 is. connected to ground in the manner'described, the brush 18'is caused to move into engagement with contact19 which is associated through "a conductor similar to 16 with the nextidle trunk; a

In the normal position of the plungerbar with the contact 23,- whereuponground projected frornbrush 20 through. contact 23,

he winding of relay 13 to battery and ground. Relay 18becomes'energizedin this circuit and establishes a holding'circuitfor itself from ground,thearmature and contact' of -relay 22, the right-hand armature andcontact of'relay1-3, and. thence over the circuit previously traced. Aconnection is at the" same time established from ground, battery,left-hand armature and alternate contact'of relay 13,'the winding ofmagnet N to ground. Magnet-N is there uponheld energized until under itsaction the plunger bar 'll'has been'returned to its normal position. andbrush 20' is again'brought into association' with contact 21. Thisactionresults in the' energization of relay 22, the consequent breakingofpthe holdingcircuit of relay13, and the retraction of the armatures ofrelay 13.

- The release of switch is accomplished the shaftl has rotated. Theretraction of its armatures by relay 7 allows the shaft 1 to move upwardand removes the force which keeps the plunger, such as I, inassociation'wi-th the contacts such as C What is claimed is: I v 1.- Ina telephone system, g up switches for interconnecting said lines andtelephone lines, of extending circuits, selective said circuitscomprising terminals in which said lines terminate, terminals arrangedin operative relation to said line terminals in which said circuitsterminate, a means for causing the operative interconnection of saidline and said circuit terminals individual to each said group ofextending circuits, means common to said groups for controlling saidmeans and means for selectively operating said first means.

2. In a telephone system, a line, a plurality of groups of trunks, anautomatic switch for establishing connection between said line and anidle one of said trunks provided with contacts in which said line andsaid trunks terminate, a series of members for operatively associatingsaid line terminals with said trunk terminals, each said member beingindividual to one of said groups of trunks, trunk controlled means foroperatively associating said members with sets of terminals connected toidle trunks, and line controlled means for selectively operating saidmembers.

3. In a telephone system, a line, a plurality of groups of trunks, anautomatic switch for establishing connections between said line and saidtrunks comprising terminals in which said line terminates, terminalsarranged in operativerelationwithsaid line terminals in which said trunkterminates, means individual to each of said groups of trunks foractuating said terminals, trunk controlled means for automaticallyassociating said means with an idle one of said trunks, and linecontrolled means for selectively operating said terminal actuatingmeans.

4. In a telephone system, telephone lines, groups of extending circuits,automatic switches for interconnecting said lines and circuits, groupsof spring contacts in which said lines and said extending circuitsterminate, means individual to each said group for operatively actuatingsaid spring con tacts to interconnect said lines and said circuits,means common to said groups for automatically associating saidmeans withcontacts connected to an idle one of said circuits, and line controlledmeans for selectively actuating said contact actuating means.

5. In a telephone system, a selective switch comprising a plurality ofgroups of banks of contacts, means individual to each bank for operatingthe contacts thereof, means common to each group for controlling saidfirst means and means individual to the corresponding bank of each groupfor selectively operating said first means.

In witness whereof, I hereunto subscribe my name this 26th day of AprilA. D., 1917.

CHARLES L. GOODRUM.

